I know that he said it was a single charge, but I wonder if this has to do with whether the pre-tip amount is pre-authorized or not. If it is a table side charge + select tip, it -should- be a single authorization and charge, but what if it isn't? Assume $100 pre-tip (post tax) authorization, then you add a $20 tip. What if Chase links the credit amount to the amount authorized first, then assumes the final posted amount is just the tip added? I think it would cause a bunch of issues, but it is technically-doable. So if the terms specifically exclude tips, this is how they could try to accomplish that (no idea how they would exclude taxes because that isn't a separate authorization, but maybe with L3 data..).

I'm with you though, I think it's supposed to be just based on the total amount charged..I wouldn't think of them breaking it out.